Midterm

Question 1

What is the common method for sterilizing common lab materials and reagents?

Answer 1

using an autoclave

Question 2

How are liquids that cannot tolerate extreme heat be sterilized?

Answer 2

can be passed through a filter to physically remove cellular organisms

Question 3

What are bacteriophages?

Answer 3

viruses that infect bacterial hosts and have properties shared by all viruses

Question 4

Bacteriophages require a _______________ to reproduce

Answer 4

bacterial host

Question 5

Bacteriophages are ____________ to replicate by themselves

Answer 5

unable

Question 6

What are two things that affect the growth rate of bacteria?

Answer 6

Temperature
exposure to oxygen

Question 7

Name two phage isolation methods

Answer 7

Enrichment
Direct isolation

Question 8

What are bacteriophages made up of?

Answer 8

Head and tails

Question 9

Name two types of phages

Answer 9

temperate
virulent

Question 10

True/false: Phages can diffuse across top agar

Answer 10

True

Question 11

True/false: phages are always able to superinfection a lysogen of the same phage

Answer 11

False - Phages are always able to superinfection a lysogen of a different phage

Question 12

What is the purpose of streaking?

Answer 12

To isolate phage from a large group

Question 13

What is the name of the bacterial host we are using? (genus and species)

Answer 13

Streptomyces miribalis
Streptomyces scabiei

Question 14

What is the purpose of a negative control?

Answer 14

To compare with other plates to see if we actually got plaques or if something got contaminated

Question 15

What is after isolation in the protocol?

Answer 15

purification

Question 16

What is the purpose of a full plate titer?

Answer 16

To determine the concentration of your phage

Question 17

What is a virulent phage?

Answer 17

a phage that only uses the lytic cycle to reproduce

Question 18

What is a temperate phage?

Answer 18

follow the lysogenic cycle

Question 19

What is the purpose of a spot test?

Answer 19

Test for the presence of a phage

Question 20

What is plaque assay?

Answer 20

Mixing phage with host bacteria and growing on agar to test for plaques.

Question 21

What are the mechanisms used by bacteria, and by bacteriophages, to prevent bacteriophage infection?

Answer 21

A mutation resulting in loss or alteration of the receptor to which the host the phage binds

CRISPR

DNA restriction-modification systems

The production of an immunity repressor protein by a prophage carried by a lysogen

Question 22

From Debarbieux: Heat killed PAK-P1 was used as a control to show what?

Answer 22

That bacteriophage must be active to cure the mice.

Question 23

From Debarbieux: The investigators use BALs when determining the amount of phage and bacteria present in the mice. What is a BAL?

Answer 23

Use of fluid to rinse and sample the interior of the lungs

Question 24

From Debarbieux: The authors tried varying the time phage was administered to the mice post infection. What was found to be the longest time they could wait and still cure 100% of the mice?

Answer 24

2 hours

Question 25

How do you isolate DNA from bacteriophages?

Answer 25

Host bacterial DNA and RNA needs to be removed from the lysate

Question 26

What does adding STOP solution do in isolating DNA?

Answer 26

inactivates and degrades nucleases

Question 27

What does the isopropanol do in isolating DNA?

Answer 27

Washes salts off the partially purified phage DNA

Question 28

What does clean-up resin do in isolating DNA?

Answer 28

degrade nucleases and capsid proteins, and resin to bind DNA

Question 29

What does the nuclease treatment of lysate do in isolating DNA?

Answer 29

Removes bacterial DNA and RNA

Question 30

What does DNase I do in isolation of DNA?

Answer 30

digests DNA

Question 31

What does RNase A do in isolation of DNA?

Answer 31

digests RNA

Question 32

What is phase A on the graph?

Answer 32

Lag phase

Question 33

What is phase B on the graph?

Answer 33

Exponential phase

Question 34

What is phase C on the graph?

Answer 34

Stationary

Question 35

What is phase D on the graph?

Answer 35

Death phase

Question 36

How do you purify a phage?

Answer 36

pick a plaque > serially dilute > plaque assay > repeat until you have three rounds of one morphology

Question 37

What is unique or interesting about that particular host(s)?

Answer 37

Resistant to high levels nickel and other heavy metals

Question 38

How do you measure DNA isolation results?

Answer 38

by using a nano drop to determine DNA concentration

Question 39

How can you determine the concentration of a phage sample?

Answer 39

(number of plaques counted / volume of the sample plated) x (10^3) x dilation factor

Question 40

What is a webbed plate?

Answer 40

plates so densely packed that that plaques cover the entire plate, leaving remnants of bacteria in a pattern that looks like a spider web

Question 41

Why do we choose a webbed plate for ‘plate harvesting?’

Answer 41

When you add PB to the plates surface, phage particles from the plaques diffuse into the buffer, which can be collected and filtered to separate the phage.

Question 42

What is a lysate?

Answer 42

a concentrated liquid sample of phage

Question 43

Why do we use top agar?

Answer 43

it is rich in nutrients and encourages bacterials growth

Question 44

How are phages stained and imaged by TEM?

Answer 44

using heavy metal salts like uranyl acetate

Question 45

Electron microscope slides are called _____________

Answer 45

grids

Question 46

What are the relationships between Streptomyces spp., sporulation, and antibiotic productions?

Answer 46

Streptomyces are made up of a chain of spores and are able to produce antibiotics

Question 47

What is a myoviridae

Answer 47

contractile tail

Question 48

What is a siphoviride

Answer 48

long tail

Question 49

What is a podoviride

Answer 49

short tail